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United States Patent |
5,700,551
|
Kukino
,   et al.
|
December 23, 1997
|
Layered film made of ultrafine particles and a hard composite material
for tools possessing the film
Abstract
Ultrafine particle-layered film for coating cutting tools. The film has
more than two layers of at least two compounds consisting mainly of
carbide, nitride, carbonitride or oxide of at least one element selected
from a group consisting of IVa group elements, Va group elements, VIa
group elements, Al, Si and B, and that each layer is made of ultrafine
particles. Ultrafine particle-layered film improves hardness, strength,
wear-resistance and heat-resistance of the tools.
Inventors:
|
Kukino; Satoru (Hyogo, JP);
Nakai; Tetsuo (Hyogo, JP);
Goto; Mitsuhiro (Hyogo, JP);
Yoshioka; Takashi (Hyogo, JP);
Setoyama; Makoto (Hyogo, JP)
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Assignee:
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Sumitomo Electric Industries, Ltd. (Osaka, JP)
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Appl. No.:
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529840 |
Filed:
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September 18, 1995 |
Foreign Application Priority Data
Current U.S. Class: |
428/212; 51/302; 51/309; 427/419.1; 427/419.2; 427/419.7; 428/216; 428/336; 428/698; 428/701; 428/702; 428/704 |
Intern'l Class: |
C23C 014/06; B23B 027/00 |
Field of Search: |
428/698,212,216,336,701,702,704
51/307,309
427/419.1,419.2,419.7
|
References Cited
U.S. Patent Documents
4268569 | May., 1981 | Hale | 428/215.
|
4334928 | Jun., 1982 | Hara et al. | 75/238.
|
4562163 | Dec., 1985 | Endo et al. | 501/96.
|
4835062 | May., 1989 | Holleck | 428/469.
|
4984940 | Jan., 1991 | Bryant et al. | 428/698.
|
Foreign Patent Documents |
0 113 660 | Jul., 1984 | EP.
| |
0 197 185 | Oct., 1986 | EP.
| |
0 310 042 | Apr., 1989 | EP.
| |
0 592 986 | Apr., 1994 | EP.
| |
0 375 155 | Jul., 1978 | FR.
| |
2 448 517 | Sep., 1980 | FR.
| |
52-43846 | Nov., 1977 | JP.
| |
53-77811 | Jul., 1978 | JP.
| |
59-57967 | Apr., 1984 | JP.
| |
5-80547 | Nov., 1993 | JP.
| |
Other References
Database WPI, Section Ch, Week 8407, "Disposable Hard Tool Tip Multiple
Hard Coating Forming Carbide Nitricarbo Nitride Group-IVA Group-VA
Group-VIA Element Top Coat Alumina", AN 84-039561, Toshiba Tungallow KK,
(Jan. 6, 1984).
Database WPI, Section CH, Week 8337, "Sinter High Speed Machining Tool
Contain Molybdenum", Derwent Publications Ltd., AN 83-760769, Nachi
Fujikoshi Corp., (Jul. 28, 1983).
Patent Abstracts of Japan, vol. 010, No. 208, (C-361), Jul. 22, 1986, "Tool
Coated With Multilayered Hard Film", Japanese 61-048568, Mar. 10, 1986.
|
Primary Examiner: Turner; Archene
Attorney, Agent or Firm: Foley and Lardner
Claims
We claim:
1. Ultrafine particle-layered film, wherein said film has more than two
layers made of ultrafine particles of a different compound consisting
mainly of a carbide, nitride, carbonitride, or oxide of at least one
element selected from a group consisting of IVa group elements, Va group
elements, VIa group elements, Al, Si, and B.
2. Ultrafine particle-layered film set forth in claim 1 wherein a thickness
of each layer is in a range of 1 nm to 100 nm.
3. Ultrafine particle-layered film set forth in claim 2 wherein the
thickness of each layer is in a range of 1 nm to 50 nm.
4. Ultrafine particle-layered film set forth in claim 3 wherein a thickness
of each layer is in a range of 1 nm to 10 nm.
5. Ultrafine particle-layered film set forth in claim 1 wherein the
particle sizes of each layer are in a range of 1 nm to 100 nm.
6. Ultrafine particle-layered film set forth in claim 1 wherein the
particle sizes of each layer are in a range of 1 nm to 50 nm.
7. Ultrafine particle-layered film set forth in claim 1 wherein the
particle sizes of each layer are in a range of 1 nm to 10 nm.
8. Ultrafine particle-layered film set forth in claim 1, wherein said
layers are alternating and repeating.
9. Ultrafine particle-layered film set forth in claim 1 wherein at least
one layer is made of a compound whose crystal structure is cubic system
and at least another one layer is made of a compound whose crystal
structure is not cubic system and/or is amorphous.
10. Ultrafine particle-layered film set forth in claim 9 wherein at least
one layer is made of a compound whose crystal structure is cubic system
and at least another one layer is made of a compound whose crystal
structure is hexagonal system.
11. Ultrafine particle-layered film set forth in claim 9 wherein said
compound whose crystal structure is cubic system is nitride, carbide or
carbonitride containing at least one element selected from a group
consisting of Ti, Zr, Cr, V, Hf, AlD and B.
12. Ultrafine particle-layered film set forth in claim 9 wherein said
compound whose crystal structure is not cubic system and/or is amorphous
is nitride, carbide or carbonitride containing at least one element
selected from a group consisting Al, Si and B.
13. Ultrafine particle-layered film set forth in claim 12 wherein said
compound whose lattice structure is not cubic system and/or amorphous is
AlN.
14. Ultrafine particle-layered film set forth in claim 1 wherein a
composition modulated layer in which composition change gradually and
continuously is interposed between adjacent two layers.
15. A method for making a coated tool, comprising applying on at least a
portion of a surface of a substrate of said tool where cutting is to be
effected said ultrafine particle-layered film.
16. The method set forth in claim 15 wherein said substrate is a CBN
sintered body containing more than 20% by volume of cubic boron nitride
(CBN), diamond sintered body containing more than 40% by volume of
diamond, silicon nitride sintered body or aluminium oxide-titanium carbide
sintered body.
17. The method set forth in claim 15 wherein said substrate is cemented
carbide, cermet or high speed steel.
18. The method set forth in claim 15 wherein a thickness of said ultrafine
particle-layered film is 0.5 .mu.m to 15 .mu.m.
19. The method set forth in claim 18 wherein said substrate is a CBN
sintered body containing 30 to 90% by volume of cubic boron nitride (CBN),
the remaining part of said CBN sintered body being a binder consisting of
at least one member selected from the group consisting of nitride,
carbide, boride and oxide of IVa, Va and VIA elements and their solid
solutions and aluminium compounds and inevitable impurities.
20. The method set forth in claim 19 wherein said binder comprises 50 to
98% by weight of at least one member selected from a group consisting of
TIC, TiN, TiCN, (TiM)C, (TiM)N and (TiM)CN in which M is a transition
metal selected from IVa, Va nd VIa elements except Ti, and 2 to 50% by
weight of aluminium compound.
21. The method set forth in claim 20 wherein said binder consists of 50 to
98% by weight of TiN, 2 to 50% by weight of aluminium compound and
inevitable impurities.
22. The method set forth in claim 18 wherein said substrate is a CBN
sintered body containing 40 to 95% by volume of cubic boron nitride (CBN),
the remaining part of said CBN sintered body being a binder selected from
the group consisting of TiN, boride or carbide of Co or W, aluminum
nitride, aluminum boride and their solid solutions and inevitable
impurities.
23. The method set forth in claim 22 wherein said binder contains 1 to 50%
by weight of TiN and at least one member selected from the group
consisting of boride and carbide of Co or W, aluminum nitride, aluminum
boride and their solid solutions.
24. The method set forth in claim 18 wherein said substrate is a CBN
sintered body containing more than 90% by volume of cubic boron nitride
(CBN), the remaining part of said CBN sintered body being a binder
comprising boride of Ia or IIa elements, TiN and inevitable impurities.
25. The method set forth in claim 24 wherein said binder contains 1 to 50%
by weight of TiN and boronitride of Ia or IIa elements.
26. The method set forth in claim 18 wherein said substrate is a diamond
sintered body containing 50 to 98% by volume of diamond, the remaining
part of said sintered body comprising an iron family element and
inevitable impurities.
27. The method set forth in claim 18 wherein said substrate is a diamond
sintered body containing 60 to 95% by volume of diamond, the remaining
part of said sintered body comprising an iron family element, at least one
carbide or carbonitride of IVa, Va and VIa elements, WC and inevitable
impurities.
28. The method set forth in claim 27 wherein said reminding part of said
diamond sintered body comprises Co, TiC, WC and inevitable impurities.
29. The method set forth in claim 18 wherein said substrate is a diamond
sintered body containing 60 to 98% by volume of diamond, the remaining
part of said diamond sintered body comprising silicon carbide, silicon, WC
and inevitable impurities.
30. The method set forth in claim 18 wherein said substrate is a sintered
body containing more than 90%by volume of silicon nitride, the remaining
part of said sintered silicon nitride body comprising at least one member
selected from the group consisting of aluminum oxide, aluminum nitride,
yttrium oxide, magnesium oxide, zirconium oxide, hafnium oxide, rear earth
elements, TiN and TiC; and inevitable impurities.
31. The method set forth in claim 18 wherein said substrate is a sintered
body made of 20 to 80% by volume of aluminum oxide and 75 to 15% by volume
of titanium carbide, the remaining part of said sintered silicon nitride
body comprising an oxide of at least one element selected from the group
consisting of Mg, Y, Ca, Zr, Ni and Ti; and inevitable impurities.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a layered film made of ultrafine particles
("ultrafine particles-layered film", hereinafter) for coating cutting
tools and a composite material for tools possessing the film which are
improved in hardness, strength, wear-resistance and heat-resistance.
The present invention is advantageously applicable to cutting tools whose
substrate is made of CBN sintered body, diamond sintered body, silicon
nitride sintered body, aluminum oxide-titanium nitride sintered body,
cemented carbide, cermets or high speed too/steel.
2. Description of the Related Art
Tools of high speed steel and cemented carbide are coated with a thin film
of carbide, nitride or carbonitride of titanium so as to improve
wear-resistance. In an application where higher hardness and higher
strength at elevated temperatures are required, tools made of sintered
body such as cubic boron nitride (CBN) sintered body, diamond sintered
body, silicon nitride sintered body and aluminum oxide-titanium carbide
are used.
However, heat-resistance and wear-resistance of known tools are becoming
insufficient for recent requirement, so that known cutting tools are
difficult to be used in sever cutting conditions including high speed
cutting and high performance cutting.
An object of the present invention is to improve wear-resistance,
heat-resistance and corrosion-resistance of cutting tools, wear-resisting
tools, sliding parts or machine parts.
Another object of the present invention is to provide a hard composite
material for tools, which possesses higher strength of base material and
is improved in wear-resistance, hardness at elevated temperatures and
corrosion-resistance, and which can be used in cutting work of hardened
steels, high-grade high-hard cast iron or other materials which are
difficult to be cut.
SUMMARY OF THE INVENTION
The present invention provides ultrafine particle-layered film,
characterized in that the film has more than two layers, each layer is
made of a compound consisting mainly of carbide, nitride, carbonitride or
oxide of at least one element selected from a group comprising IVa group
elements, Va group elements, VIa group elements, Al, Si and B, and each
layer is made of ultrafine particles.
The present invention provides also a hard composite material for tool
coating, characterized in that the tool has the ultrafine particle-layered
film on at least a portion of a surface of substrate of tool where cutting
is effected.
The ultrafine particle-layered film according to the present invention is
based on a novel idea and is different from known concepts. Therefore, the
ultrafine particle-layered film and the hard composite material for tool
coating according to the present invention will be explained with
referring to FIG. 1 and 2.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an illustrative cross sectional view of a hard composite material
for tool coating including a ultrafine particle-layered film according to
the present invention.
FIG. 2 is an enlarged illustrative cross sectional view of a ultrafine
particle-layered film according to the present invention.
FIG. 3 is a view similar to FIG. 2 but the ultrafine particle-layered film
has a composition modulated layer.
FIG. 4 is a view similar to FIG. 2 but the ultrafine particle-layered film
has a mixed layer.
FIG. 5 illustrates first embodiment of an apparatus for preparing the
ultrafine particle-layered film according to the present invention.
FIG. 6 illustrates second embodiment of the apparatus for preparing the
ultrafine particle-layered film according to the present invention.
FIG. 1 illustrates a cross sectional view of a hard composite material for
tool coating according to the present invention. The hard composite
material comprises a ultra fine particle-layered film (1) consisting of
unit layers (a) and (b) deposited alternatively and repeatedly on a
substrate (2). An intermediate layer (3) and a surface layer (4) can be
formed optionally. Each layer (a) or (b) of the ultrafine particle-layered
film is emphasized in FIG. 1 but its actual thickness is 1 nm to 100 nm,
more preferably 1 nm to 50 nm, and more preferably 1 nm to 10 nm which is
about 1/100 of thickness of the intermediate layer (3) which is 0.05 .mu.m
to 5 .mu.m thick and thickness of the surface layer (4) which is 0.1 .mu.m
to 5 .mu.m thick respectively.
FIG. 2 is an illustrative enlarged cross section of the ultrafine
particle-layered film (1). As is seen in FIG. 2, each layer (a) and (b) of
the ultrafine particle-layered film (I)consists of ultrafine particles. In
FIG. 2, "d.sub.1 " and "d.sub.2 " are particle sizes of particles for each
layer (a) and (b). A graph shown at fight side of FIG. 2 illustrates a
variation in composition in the ultrafine particle-layered film along the
thickness direction. One can understand that proportions of elements in
two layers "a" (solid line) and "b" (dotted line) are repeated alternately
along the thickness direction.
The ultrafine particle-layered film according to the present invention have
preferably at least one layer made of a compound whose crystal structure
is cubic system and at least another one layer made of a compound whose
crystal structure is not cubic system and/or is amorphous. The compound of
non-cubic system is preferably compounds whose crystal structure is
hexagonal system.
The compound whose crystal, structure is cubic system is preferably
nitride, carbide or carbonitride containing at least one element selected
from a group comprising Ti, Zr, Cr, V, Hf, Al and B. The compound whose
crystal structure is not cubic system or of amorphous is preferably
nitride, carbide or carbonitride containing at least one element selected
from a group comprising Al, Si and B, in particular aluminium nitride
(AlN).
Particle size of each layer can be nearly equal to a thickness of each
layer and/or can be different in two layers. Alignment of the lattices of
adjacent particles is not specially required.
Each layer of the ultrafine particle-layered film according to the present
invention can be a composition modulated layer in which composition change
gradually and continuously between adjacent two layers or can has a mixed
layer of adjacent two layers.
FIG. 3 and FIG. 4 illustrate structures of the ultrafine particle-layered
film having the composition modulated layer and the mixed layer
respectively. The composition modulated layer or the mixed layer (c) is
interposed between adjacent layers (a) and (b),
The compound from which each layer of the ultrafine particle-layered film
is made can consist of different elements or can contain common
element(s). For example, two layers can be TiC and AlN or can be (Ti.sub.x
Al.sub.1-x)N and (Ti.sub.y Al.sub.1-y)N in which 0.ltoreq.x, y.ltoreq.1
and x.noteq.y.
The ultrafine particle-layered film can consist of two compounds repeated
alternately or of more than three compounds repeated successively.
Preferably, at least one compound is a compound having mainly metallic
bond property and at least another one compound is a compound having
mainly covalent bond property. For example, preferably, the former is TiN
and the later is AlN.
Lamination cycle can be maintained at a constant value or can be changed
regularly or irregularly, if necessary. "Lamination cycle" is a distance
between one layer and next layer of the same compound (a). In case of FIG.
2, the lamination cycle is a repeating unit of successive two layers (a)
and (b) and is a sum .lambda. of their thickness ›.lambda.=(a)+(b) !.
The optimum ratio of unit layers in thickness (for example, a ratio of
thickness of (a) to (b) of FIG. 1) depends on combination of compounds and
properties required in the ultrafine particle-layered film. Generally, the
ratio is within 1:10 to 10:1.
The ultrafine particle-layered film can be prepared by physical vapour
deposition (PVD) technique such as sputtering and ion-plating which
permits to perform surface-treatment of substrate or tool without
deteriorating its inherent strength and high-resistances to wear and
breakage. In PVD, arc-ion plating which can highly ionize material
elements is preferably used. The arc-ion plating technique permits to
increase adhesion to the substrate and to improve crystallinity of a film
deposited.
In particular, reactive PVD technique is preferably used. In fact, higher
ionization rates can be obtain by the reactive PVD technique in which a
target or plural targets of metal or alloy containing at least one
elements selected from IVa, Va, VIa elements, Al, Si and B is used
together with a gas containing at least one of C, N and O as materials.
Other gas than material gas, such as inert gas of Ar and He and etchant
gas of H.sub.2 can be introduced into a film-forming chamber.
When the ultrafine particle-layered film according to the present invention
is applied to cutting tools, in particular to cutting tips, it is
preferable to coat face and flank of the tip with different ultrafine
particle-layered films possessing different lamination cycles which depend
to properties required in face and flank respectively.
FIG. 5 is an illustrative view of first embodiment of an apparatus for
producing the ultrafine particle-layered film according to the present
invention. In this embodiment, each substrate (12) such as tool or tip is
held on a periphery of a rotary holder (15). While the rotary holder (15)
is rotated, vapor of Al and Ti are created from two vapour sources (10,
11) and also are discharge is created by an arc electrode (20) in nitrogen
gas atmosphere so that ultra thin films of AlN and TiN are deposited
alternately on a surface of the substrate (12). In this embodiment, a
shade or mask (16) is used so as to produce a ultrafine particle-layered
film having substantially no composition modulated layer (a/b/a/ - - - ).
Or, a ultrafine particle-layered film (1) (FIG. 1) having a distribution
in composition shown in the right side of FIG. 2. is formed on the
substrate (2).
FIG. 6 is an illustrative view of second embodiment of the apparatus for
producing the ultrafine particle-layered film according to the present
invention. This second embodiment differs from the first embodiment in
that composition modulated layers (c) can be formed in this case. In fact,
four vapour sources (10, 10', 11, 11') of Al and Ti surround the rotary
holder (15) so that the composition modulated layers (c) are formed at
zones where both vapor of Ti and Al arrive to produce a nitride of Ti and
Al. FIG. 3 and FIG. 4 illustrate ultrafine particle-layered films obtained
by this embodiment and each graph shown at the right side of these figures
shows a distribution in components of the resulting ultrafine
particle-layered film.
At least one intermediate layer (3) having a thickness of 0.05 .mu.m to 5
.mu.m is preferably interposed between the substrate (2) and the ultrafine
particle-layered film (1). This intermediate layer (3) is preferably made
of a material selected from a group comprising boride, nitride, carbide
and oxide of IVa, Va and VIa elements and their solid solutions. The
intermediate layer (3) functions to increase adhesion between the
ultrafine particle-layered film (1) and the substrate (2). Such
intermediate layer is expected to reduce residual stress in the film
deposited on a substrate which differs from the film in its property by
assuring gradual control of its properties.
A surface layer (4) having a thickness of 0.1 .mu.m to 5 .mu.m can be
deposited on an outer surface of the ultrafine particle-layered film (1).
The surface layer (4) is preferably made of a material selected from a
group comprising nitride, carbide, carbonitride and oxide of IVa, Va and
VIa elements.
Nitride, carbide, carbonitride and oxide of IVa, Va and VIa elements are
very hard so that they are expected to be used as wear-resisting coating
materials. The present invention is characterized in that at least two
compounds are deposited alternately in a form of ultrafine
particle-layered film consisting of a plurality layers each having a
thickness of nanometer order and consisting of fine particles possessing
particle size of nanometer order. The ultrafine particle-layered film
shows improved strength, wear-resistance, tenacity and resistance to
breakage.
According to the present invention it is believed that by laminating more
than two compounds each having different mechanical properties such as
elastic constants and Poisson's ratios and each consisting of fine
particles having particle sizes of nanometer order so that each layer has
a thickness of nanometer order, resistance to propagation of dislocation
in each layer can be increase, or dislocation is prevented, or dislocation
which propagate between adjacent layers or adjacent particles can be
arrested at interface of adjacent layers and/or at grain boundary, so that
plastic deformation of the film can be decreased. Development of crack can
be arrested at the interfaces so that fracture-resistance of the film is
improved.
Advantages of the present invention can not be obtained when the thickness
of each layer is not higher than 1 nm, because a stratified structure
disappears. It is also confirmed that the advantages of the present
invention can not be obtained even if diffusion of consistent elements is
reduced to very low level if the thickness is not higher than 1 nm. On the
contrary, if the thickness of each layer exceeds 50 nm, the effect to
prevent dislocation is lost. Therefore, the thickness of each layer must
be in a range of 1 nm to 50 nm.
Still more, if the particle size of particles of which each layer is made
is not higher than 1 nm, structure of each particle becomes very unstable
and a particulate structure disappears due to diffusion, or the particles
size increases due to recombination of adjacent particles so that the
resulting particle has a particle size of higher than 1 nm. Remarkable
advantage in wear-resistance is not recognized even if fine particles
having particle sizes of lower than 1 nm are produced. On the contrary, if
the particle size exceeds 50 nm, the effects to prevent dislocation and
crack is lowered. Therefore, it is preferable to select the particle size
of each particle in a range of 1 nm to 50 nm.
There is no special limitation in a relation between the thickness of each
layer and the particle size. However, excessive growth of a particle over
a thickness result in disorder of stratified structure. Therefore, the
maximum particle size is preferably the same value as the thickness, is at
most about 1.1 times of the thickness or less.
Japanese patent laid-open No. 5-80547 discloses a multi-layered protective
film or fine particle dispersion film. In this patent, however, the
protective film must have an interface which is coherent to lattices of
crystals. In the present invention, the above-mentioned advantages can be
realized only when two of the stratified structure and the ultrafine
particle structure are realized simultaneously. In other words, the
above-mentioned advantages can not be obtained by one of the stratified
structure an-d the ultrafine particle structure alone.
Still more, in the present invention, coherency to lattices of crystals at
interface is not required and, in some eases, there is such danger that
advantages of the present invention are lost if an interface between
particles in a layer is coherent. In other words, the present invention is
different from the idea disclosed in Japanese patent laid-open No. 5-80547
in which existence of coherent interface is indispensable.
Therefore, the ultrafine particle-layered film according to the present
invention is advantageously formed on a tool having a substrate made of
CBN sintered body, diamond sintered body, silicon nitride sintered body,
aluminium oxide-titanium carbide sintered body cemented carbide, cermets
or high speed steel at least a portion where cutting is effected, so as to
improve wear-resistance, machinability and fracture-resistance and to
increase tool life.
The above-mentioned advantages become remarkable when one layer to be
stratified has a crystal structure of cubic system and another layer has a
crystal structure of other than the cubic system and/or is amorphous due
to their mechanical properties or anisotropy in mechanical properties
caused by anisotropy in crystal structure. The crystal structure other
than the cubic system is preferably hexagonal.
Nitride, carbide and carbonitride of Ti, Zr, Cr, V or Hf have a crystal
structure of cubic system and possess improved hardness, heat-resistance,
resistance to oxidation and chemical resistance. Therefore, these
materials are suitable to prepare the ultrafine particle-layered film
according to the present invention. Nitride, carbide and carbonitride of
their alloys or alloy with Al are suitable because it is known that they
are better in the above-mentioned properties. Cubic boron nitride (CBN)
which is a nitride of B is the hardest material next to diamond and
possesses higher heat-resistance and oxidation-resistance than diamond. It
is easily estimated that alloy compounds between these compounds and B
also may possess superior properties. Therefore, these materials also are
suitable to prepare the ultrafine particle-layered film according to the
present invention
As the compound whose crystal structure is not cubic system or amorphous,
carbide, nitride or carbonitride of Al, Si or B show improved hardness,
chemical stability and heat-resistance. In particular. AlN possessing
hexagonal crystal structure is suitable to combined with the metallic bond
compound having cubic system since AlN is improved in the above-mentioned
properties and possess covalent bond property. AlN has Wurtzite type
structure under an equilibrium eonctition at ambient temperature and
pressure but has NaCl type structure at elevated pressure. It is reported
treat Wurtzite type (hexagonal system) AlN has a property to produce an
inclined wave without creating shock wave when it is compressed with
impact, resulting in that the ultrafine particle-layered film according to
the present invention can be protected from impact damage and hence
wear-resistance and breakage-resistance are advantageously improved.
Preferred compound is nitride of Ti and Al and in particular Ti.sub.x
Al.sub.1-x N (x>0.25) having cubic structure and Ti.sub.y Al.sub.1-y N
(y.ltoreq.0.25) having hexagonal structure
Compounds improved in oxidation-resistance and chemical stability of the
above-mentioned compounds, by adding a small amount of rare earth elements
such as yttrium or oxygen, provided that their crystal structure and
properties are not influenced badly, are also suitable to improve the
properties of the ultrafine particle-layered film according to the present
invention.
When separation of adjacent layers occur at the interface between adjacent
two layers where mechanical properties change, it is preferable to
interpose, between adjacent two layers, a composition modulated layer in
which composition changes gradually and continuously or a mixed layer in
which compounds of adjacent layers are mixed. This solution improves
resistance to separation and reduces wear caused by micro flaking.
Therefore, the ultrafine particle-layered film according to the present
invention permits to improve wear-resistance, oxidation-resistance,
fracture-resistance and resistance to welding and to increase tool life
for tools having a substrate made of cemented carbide, cermets and high
speed steel.
It is known that hardness of a thin film is influenced by the hardness of a
substrate on which the tin film is deposited and this influence become
accelerated greatly with decrement of thickness of the thin film, so that
the hardness of thin film approach to the hardness of substrate.
Therefore, it is preferable to use a substrate made of CBN sintered body,
diamond sintered body, silicon nitride sintered body or aluminium
oxide-titanium carbide sintered body which possesses very high hardness at
elevated temperatures, so as to maintain high hardness and to improve
wear-resistance of the ultrafine particle-layered film according to the
present invention at elevated temperature.
In the hard composite material for tools according to the present
invention, if the thickness of the ultrafine particle-layered film is not
higher than 0.5 .mu.m, no improvement in adhesion is observed. On the
contrary, if the thickness of the ultrafine particle-layered film exceeds
15 .mu.m, adhesion to the substrate become lower because of influence of
residual stress in the ultrafine particle-layered film and advantage of
the ultrafine particle-layered film can not be expected so that
wear-resistance become lower. Therefore, the thickness of the ultrafine
particle-layered film is preferably in a range of 0.5 .mu.m to 15 .mu.m.
Improvement in adhesion of the intermediate layer (3) is not observed when
the thickness thereof is not higher than 0.05 .mu.m and exceeds 5 .mu.m.
Therefore, the thickness of the intermediate layer (3) is preferably
selected in a range between 0.05 and 5 .mu.m from the view point of
productivity. The thickness of the surface layer (4) formed on the
ultrafine particle-layered film according to the present invention is
preferably in a range between 0.1 .mu.m and 5 .mu.m. Improvement in
wear-resistance is not observed in a thickness of not higher than 0.1
.mu.m. Thickness of more than 5 .mu.m also show no improvement in
wear-resistance due to peel-off or other reasons.
The hard composite material for tools according to the present invention
can be shaped or machined into and advantageously used as cutting tools
such as tip, drills and end mills. It was confirmed that tools prepared
from the hard composite material for tools according to the present
invention show surprisingly superior cutting performance and long lives.
In a cutting tip, it is confirmed that the cutting performance and life of
the cutting tip increase remarkably when the lamination cycle of the
ultrafine particle-layered film at the face is bigger than the lamination
cycle at the flank. In a different tip having a different shape and
application, the cutting performance and life of the cutting tip increase
remarkably when the lamination cycle at the flank is bigger than the
lamination cycle at the face. This means that required properties such as
wear-resistance and acid-resistance for the face and flank are depend to
applications and optimum lamination cycle may be different from each
other.
The substrate (2) can be selected from following preferable three CBN
sintered bodies (1) to (3):
(1) CBN sintered article containing 30 to 90% by volume of cubic boron
nitride (CBN), reminding parts being a binder consisting of at least one
member selected from a group comprising nitride, carbide, boride and oxide
of IVa, Va and VIa elements and their solid solutions and aluminium
compound, and inevitable impurities. The binder consist preferably of 50
to 98% by weight of at least one member selected from a group comprising
TiC, TiN, TiCN, (TiM)C, (TiM)N and (TiM)CN in which M is a transition
metal selected from IVa, Va nd VIa elements except Ti and 2 to 50% by
weight of aluminium compound.
(2) CBN sintered body containing 40 to 95% by volume of cubic boron nitride
(CBN), reminding parts being at least one binder selected from a group
comprising TiN, boride and carbide of Co or W, aluminum nitride, aluminum
boride and their solid solutions and inevitable impurities. The binder
contains preferably 1 to 50% by weight of TiN.
(3) CBN sintered body containing more than 90% by volume of CBN crystalline
particles, reminding parts being a binder consisting of boronitride of Ia
or IIa elements and TiN and inevitable impurities. The binder contains
preferably 1 to 50% by weight of TiN. CBN sintered body of the type (1)
itself is known and its properties and its production method are described
in details in the Japanese patent publication-A-53-77811.
CBN sintered body of the type (2) can be prepared by adding TiN to a binder
disclosed in the Japanese patent patent publication-B-52-43846. Addition
of TiN increase adhesion to the laminated film (1) of the present
invention.
CBN sintered body of the type (3) can be prepared by adding TiN to a binder
disclosed in the Japanese patent publication-A-59-57967. Addition of TiN
increase adhesion to the laminated film (1) in this type CBN sintered body
also.
The substrate (2) can be following diamond sintered bodies containing more
than 40% by volume of diamond:
(1) a diamond sintered body containing 50 to 98% by volume of diamond,
reminding being preferably iron family element and inevitable impurities.
The iron family element is preferably Co.
(2) a diamond sintered body containing 60 to 95% by volume of diamond,
reminding comprising preferably iron family element, at least one member
selected from a group comprising carbide and carbonitride of IVa, Va and
VIa elements, WC and inevitable impurities.
(3) a diamond sintered body containing 60 to 98% by volume of diamond,
reminding comprising preferably silicon carbide, silicon, WC and
inevitable impurities.
The diamond sintered bodies possess particularly, higher strength among
known diamond sintered bodies and contain at least one member selected
from a group comprising iron family element, carbide and carbonitride of
IVa, Va and VIa elements, silicon nitride and silicon. It was confirmed
also that these materials are effective to bond the ultrafine
particle-layered film to the substrate.
It is preferable to interpose an intermediate layer (3) having a thickness
of 0.05 .mu.m and 5 .mu.m and made preferably of a material selected from
a group comprising boride, nitride, carbide and oxide of IVa, Va and VIa
elements and their solid solutions between the substrate (2) and the
ultrafine particle-layered film (1) so as to improve bonding strength.
The substrate (2) can be a silicon nitride sintered body containing 90% by
volume of silicon nitride, preferably prepared by the technique of HIP.
Reminding of this silicon nitride sintered body comprise at least one
member selected from a group comprising aluminum oxide, aluminum nitride,
yttrium oxide, magnesium oxide, hafnium oxide, rear earth and inevitable
impurities.
Onto the silicon nitride sintered body, an intermediate layer (3) having a
thickness of 0.05 .mu.m and 5 .mu.m and made preferably of a material
selected from a group comprising boride, nitride, carbide and carbonitride
of IVa, Va and VIa elements is deposited, and then the ultrafine
particle-layered film can be deposited by using an apparatus shown in FIG.
5 and FIG. 6.
TiN can be added to the silicon nitride sintered body so as to improve
adhesion to the ultrafine particle-layered film.
The substrate (2) can be a sintered body made of 20 to 80% by volume of
aluminum oxide and 75 to 15% by volume of titanium carbide. Reminding of
this sintered body can be oxide of at least one element selected from a
group comprising Mg, Y, Ca, Zr, Ni and Ti and inevitable impurities.
Preferable sintered body comprises 65 to 70% by volume of aluminum oxide
and 30 to 25% by volume of titanium carbide, reminding being oxide of Mg,
Y or Ca and inevitable impurities.
TiN can be added to the aluminum oxide-titanium carbide sintered body so as
to improve adhesion to the ultrafine particle-layered film.
Thus, the hard composite material for tool coating according to the present
invention has a layered structure consisting very thin unit layers each
consisting of ultrafine particles and which can improve resistances to
heat, welding, oxidation, breakage and micro-chipping and improve sliding
property, still more, possesses tenacity as well as equal or higher
hardness than the conventional hard coats, and can be prepared by PVD
technique, so that cutting tools or wear-resisting tools having the hard
composite material for tool coating according to the present invention
show long tool lives.
The hard composite material for tool coating according to the present
invention can be used to sliding parts whose surface is required to be
resistant to wear so as to elongate its life in addition to cutting tools
and wear-resisting tools.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will be described in more details with referring to
Examples but the present invention is not limited to these Examples.
In Examples, the thickness of each layer and the particle size of each
particle were determined by a transmission electron microscope (TEM), a
variation in composition was measured by a micro area energy dispersion
type X-ray analyzer (EDX) installed in the transmission electron
microscope. The variation in composition can be determined by ESCA or SIMS
also.
Crystal structure in the ultrafine particle-layered film was determined
from X-ray diffraction pattern and from transmission electron scattering
pattern in a micro area by using the transmission electron microscope. The
X-ray diffraction pattern was obtained by using Cu target and a diffract
meter of nickel filter (Cu-K.alpha., .theta.-2.theta.).
EXAMPLE 1
On a cutting tip of cemented carbide having a composition of JIS P30 and a
shape of ISO SNGN120408, a ultrafine particle-layered film according to
the present invention was deposited by ion plating with vacuum are
discharge.
As is shown in FIG. 5 or FIG. 6, a plurality of targets 10(10'), 11(11')
were set in a vacuum chamber and a plurality of the cutting tips (12) were
held on a rotary holder (15) arranged at the center of the targets.
Thickness and particle size in each layer and variation in composition
were controlled by adjusting revolution number of the rotary holder (15),
current density of vacuum discharge (evaporation rate of target
materials), position and number of the targets and atmosphere pressure.
In operation, after the vacuum chamber of FIG. 5 or FIG. 6 was evacuated to
a pressure of 10.sup.-5 Torr, argon (Ar) gas was introduced to create a
pressure of 10.sup.-2 Torr, the tips were heated to 500.degree. C. and a
voltage of -1,000 V was applied to the tips to cleaned surface of the
tips. After then, argon gas was evacuated. Then, at least one of nitrogen
(N.sub.2) gas, CH.sub.4 gas and Ar gas was introduced at a rate of 200
cc/min in a function of the revolution number of the rotary holder and of
time and simultaneously targets of IVa, Va or VIa elements, Al, silicon or
their alloys were vaporized and ionized in arc discharge, so that a
reaction product between the target materials and N or C in the gas was
deposited on the rotating tips when the tips passes through respective
targets.
For comparison, the conventional coating films were deposited on tips
prepared by the same method (Sample No. 50 to 52). Sample No. 50 was
prepared by known CVD technique in which a combination of TiN and Al.sub.2
O.sub.3 was deposited as a hard coat layer. In Sample No. 51, layers of
TiN and TiAlN were coated by known ion plating with vacuum arc discharge
technique on the same tip having the same composition and same shape.
Sample No. 52 was prepared by known sputtering technique by using two
targets of TiC and ZrN.
Table 1 shows ultrafine particle-layered films (Samples No. 1 to 49)
prepared as above.
Table 2 shows thickness and particle size of each layer were determined by
a transmission electron microscope.
The results of flank wear-resistance tests (continuous cutting and
intermittent cutting) of the resulting tips also are summarized in Table
2. The wear-resistance test was effected on following conditions:
______________________________________
continuous cutting
intermittent cutting
______________________________________
test piece SCM 435 SCM 435
cutting velocity (m/min)
230 230
feed (mm/rev) 0.35 0.3
cut depth (mm)
2 1.5
cutting time duration (min)
15 20
______________________________________
TABLE 1
__________________________________________________________________________
sample
Intermediate layer
Surface layer
Wear-resitant layer
No material
thickness (.mu.m)
material
thickness (.mu.m)
material thickness (.mu.m)
__________________________________________________________________________
1 none
-- none
-- ultrafine particle-layered film
3.9
2 none
-- none
-- ultrafine particle-layered film
3.8
3 none
-- none
-- ultrafine particle-layered film
4.1
4 none
-- none
-- ultrafine particle-layered film
4.2
5 none
-- none
-- ultrafine particle-layered film
3.8
6 none
-- none
-- ultrafine particle-layered film
3.7
7 none
-- none
-- ultrafine particle-layered film
3.7
8 none
-- none
-- ultrafine particle-layered film
3.6
9 none
-- none
-- ultrafine particle-layered film
3.6
10 none
-- none
-- ultrafine particle-layered film
4.1
11 none
-- none
-- ultrafine particle-layered film
3.8
12 TiN 0.02 none
-- ultrafine particle-layered film
7.2
13 TiN 0.05 none
-- ultrafine particle-layered film
6.9
14 TiN 0.1 none
-- ultrafine particle-layered film
7.5
15 TiN 0.3 none
-- ultrafine particle-layered film
7.5
16 TiN 0.5 none
-- ultrafine particle-layered film
7.7
17 TiN 1.0 none
-- ultrafine particle-layered film
7.8
18 TiN 2.0 none
-- ultrafine particle-layered film
7.6
19 TiN 5.0 none
-- ultrafine particle-layered film
8.1
20 TiN 10.0 none
-- ultrafine particle-layered film
7.6
21 TiN 0.5 none
-- ultrafine particle-layered film
0.2
22 TiN 0.5 none
-- ultrafine particle-layered film
0.5
23 TiN 0.5 none
-- ultrafine particle-layered film
2.0
24 TiN 0.5 none
-- ultrafine particle-layered film
4.0
25 TiN 0.5 none
-- ultrafine particle-layered film
8.0
26 TiN 0.5 none
-- ultrafine particle-layered film
15.0
27 TiN 0.5 none
-- ultrafine particle-layered film
20.0
28 TiN 0.5 TiCN
0.05 ultrafine particle-layered film
11.1
29 TiN 0.5 TiCN
0.1 ultrafine particle-layered film
11.2
30 TiN 0.5 TiCN
0.5 ultrafine particle-layered film
11.0
31 TiN 0.5 TiCN
1.0 ultrafine particle-layered film
11.0
32 TiN 0.5 TiCN
3.0 ultrafine particle-layered film
11.0
33 TiN 0.5 TiCN
5.0 ultrafine particle-layered film
10.9
34 TiN 0.5 TiCN
10.0 ultrafine particle-layered film
10.9
35 none
-- none
-- ultrafine particle-layered film
3.5
36 none
-- none
-- ultrafine particle-layered film
3.1
37 none
-- none
-- ultrafine particle-layered film
3.3
38 TiN -- TiCN
0.5 ultrafine particle-layered film
3.1
39 TiN 0.5 TiCN
0.5 ultrafine particle-layered film
3.2
40 TiN 0.5 TiCN
0.5 ultrafine particle-layered film
3.4
41 TiN 0.5 TiCN
0.5 ultrafine particle-layered film
3.2
42 TiN 0.5 TiCN
0.5 ultrafine particlc-layered film
3.4
43 TiN 0.5 TiCN
0.5 ultrafine particle-layered film
3.6
44 TiN 0.5 TiCN
0.5 ultrafine particle-layered film
3.5
45 TiN 0.5 TiCN
0.5 ultrafine particle-layered film
3.5
46 TiN 0.5 TiCN
0.5 ultrafine particle-layered film
3.5
47 TiN 0.5 TiCN
0.5 ultrafine particle-layered film
3.6
48 TiN 0.5 TiCN
0.5 ultrafine particle-layered film
3.7
49 TiN 0.5 TiCN
0.5 ultrafine particle-layered film
3.5
50 none Al.sub.2 O.sub.3
0.5 TiN 3.2
51 TiN 0.5 none
-- TiAlN 4.0
52 none
-- none
-- multi-layered film
5.0
__________________________________________________________________________
TABLE 2
__________________________________________________________________________
Wear-resitant layer (structure of ultrafine particle-layered film)
Maximum
materials thickness
partilce size Flank wear (mm)
of each layer
(nm) (nm) Crystal structure
continuous
off & on
No
(a) (b) (a)
(b)
(a)
(b)
(a) (b) cutting
cutting
__________________________________________________________________________
1 TiN AlN 0.8
1.0
0.8
1.0
cubic
hexagonal
0.20 0.22
2 TiN AlN 1.0
1.0
1.0
1.0
cubic
hexagonal
0.13 0.12
3 TiN AlN 5.2
3.1
5.2
3.1
cubic
hexagonal
0.10 0.11
4 TiN AlN 5.1
6.1
5.1
6.1
cubic
hexagonal
0.09 0.10
5 TiN AlN 9.8
12.1
9.8
12.1
cubic
hexagonal
0.12 0.12
6 TiN AlN 18.0
18.1
18.0
18.1
cubic
hexagdnal
0.11 0.12
7 TiN AlN 24.5
5.2
24.5
5.2
cubic
hexagonal
0.12 0.11
8 TiN AlN 50.0
41.4
50.0
41.4
cubic
hexagonal
0.13 0.12
9 TiN AlN 85.6
50.0
85.6
50.0
cubic
hexagonal
0.22 0.24
10
TiN AlN 100.0
80.7
100.0
80.7
cubic
hexagonal
0.30 0.28
11
TiN AlN 5.0
10.0
5.0
15.0
cubic
hexagonal
0.18 0.22
12
HfN AlN 6.2
5.0
6.2
5.0
cubic
hexagonal
0.31 0.29
13
HfN AlN 6.2
5.0
6.2
5.0
cubic
hexagonal
0.12 0.11
14
HfN AlN 6.2
5.0
6.2
5.0
cubic
hexagonal
0.10 0.11
15
HfN AlN 6.2
5.0
6.2
5.0
cubic
hexagonal
0.10 0.10
16
HfN AlN 6.2
5.0
6.2
5.0
cubic
hexagonal
0.09 0.08
17
HfN AlN 6.2
5.0
6.2
5.0
cubic
hexagonal
0.10 0.11
18
HfN AlN 6.2
5.0
6.2
5.0
cubic
hexagonal
0.12 0.12
19
HfN AlN 6.2
5.0
6.2
5.0
cubic
hexagonal
0.13 0.13
20
HfN AlN 6.2
5.0
6.2
5.0
cubic
hexagonal
0.25 0.27
21
TiHfN
AlN 32.0
25.9
32.0
25.9
cubic
hexagonal
0.33 0.31
22
TiHfN
AlN 32.0
25.9
32.0
25.9
cubic
hexagonal
0.13 0.12
23
TiHfN
AlN 32.0
25.9
32.0
25.9
cubic
hexagonal
0.11 0.10
24
TiHfN
AlN 32.0
25.9
32.0
25.9
cubic
hexagonal
0.11 0.10
25
TiHfN
AlN 32.0
25.9
32.0
25.9
cubic
hexagonal
0.10 0.10
26
TiHfN
AlN 32.0
25.9
32.0
25.9
cubic
hexagonal
0.13 0.14
27
TiHfN
AlN 32.0
25.9
32.0
25.9
cubic
hexagonal
0.22 0.25
28
CrN AlN 6.2
5.0
7.0
9.1
cubic
hexagonal
0.23 0.21
29
CrN AlN 6.2
5.0
7.0
9.1
cubic
hexagonal
0.12 0.12
30
CrN AlN 6.2
5.0
7.0
9.1
cubic
hexagonal
0.14 0.13
31
CrN AlN 6.2
5.0
7.0
9.1
cubic
hexagonal
0.13 0.13
32
CrN AlN 6.2
5.0
7.0
9.1
cubic
hexagonal
0.12 0.13
33
CrN AlN 6.2
5.0
7.0
9.1
cubic
hexagonal
0.12 0.14
34
CrN AlN 6.2
5.0
7.0
9.1
cubic
hexagonal
0.34 0.33
35
TiAlN*
TiAlN**
5.0
6.0
5.0
6.0
cubic
hexagonal
0.10 0.09
36
TiCN TiAlCN
7.0
5.0
7.0
5.0
cubic
hexagonal
0.09 0.10
37
TiAlN***
AlN 4.0
8.0
4.0
8.0
cubic
hexagonal
0.09 0.09
38
TiN TiC 11.0
10.0
11.0
10.0
cubic
cubic 0.13 0.12
39
TiN CrN 1.0
1.0
1.0
0.7
cubic
cubic 0.24 0.27
40
TiN CrN 10.0
7.2
10.0
7.0
cubic
cubic 0.10 0.09
41
TiN ZrN 15.0
8.5
15.0
8.5
cubic
cubic 0.15 0.14
42
CrN VN 7.2
22.0
7.2
22.0
cubic
cubic 0.16 0.15
43
TiCN HfCN 5.4
2.0
5.4
2.0
cubic
cubic 0.10 0.11
44
HfC ZrC 32.0
10.0
32.0
10.0
cubic
cubic 0.15 0.14
45
a CrN Si.sub.3 N.sub.4
45.0
21.2
45.0
21.2
cubic
hexagonal
0.14 0.15
b TiCN BN 12.5
15.3
12.5
15.3
cubic
amorpyous
0.12 0.13
c TiCN CN 12.8
11.0
12.8
15.3
cubic
amorpyous
0.14 0.13
d TiCN C 8.5
7.7
8.5
7.7
cubic
amorpyous
0.17 0.16
e C AlN 9.7
7.7
9.7
7.7
cubic
hexagonal
0.15 0.16
46
TiCrCN
HfAlCN
2.5
7.2
2.5
7.2
cubic
cubic 0.10 0.10
47
TiN--AlN--
15.0
20.0 cubic -
AlN--TiAlN 12.0
20.0
hexagonal
0.11 0.10
48
TiZrN--TiZrCrN--
23.2
5.0 cubic -
--CrN--TiZrCrN 15.4
5.0
cubic
0.10 0.11
49
HfN 8.9 8.9 cubic -
HfCrN 12.1 12.1
cubic -
CrN 15.0 15.0
cubic 0.11 0.12
50
-- -- -- -- 0.30 broken
51
-- -- -- -- 0.35 0.30
52
TiC ZrN 2.0
3.0
-- pilar growth
0.25 0.27
__________________________________________________________________________
Note:
TiHfN: (Ti.sub.0.7 Hf.sub.0.3)N
HfCN: Hf(C.sub.0.4 N.sub.0.6)
TiAlN*: (Ti.sub.0.8 Al.sub.0.2)N
TiCrCN: (Ti.sub.0.7 Cr.sub.0.3)(C.sub.0.1 N.sub.0.9)
TiAlN**: (Ti.sub.0.1 Al.sub.0.9)N
HfAlCN: (Hf.sub.0.3 Al.sub.0.7)(C.sub.0.1 N.sub.0.9)
TiCN: Ti(C.sub.0.5 N.sub.0.5)
HfCrN: (Hf.sub.0.6 Cr.sub.0.4)N
TIAlN***: (Ti.sub.0.7 Al.sub.0.3)N
TiAlCN: (Ti.sub.0.5 Al.sub.0.5)(C.sub.0.5 N.sub.0.5)
The results summarized in Table 1 and Table 2 reveal that the conventional
tip (Sample No. 50) whose hard coating layer was prepared by the
conventional PVD technique has not sufficient resistance to breakage
because its base material deteriorate in tenacity. On the contrary, tips
according to the present invention (Sample No. to 49) show superior
wear-resistance in both of continuous and intermittent cutting operations
and also show improved resistance to breakage since their hard coat layers
were prepared by PVD technique which can reserve the tenacity of base
material.
The results of Sample No. 1 to 10 reveal that thickness of the ultrafine
particle-layered film according to the present invention is preferably in
a range of 1 nm to 50 nm. In fact, Sample No. 11 shows lower
wear-resistance because the maximum particle size of a AlN particle in its
ultrafine particle-layered film was bigger than a thickness of the layer
of AlN, so that no clear stratified structure was observed. Sample No. 39
also showed lower wear-resistance because the maximum particle size of
particles in CrN layer was only 0.7 nm.
The results of Sample No. 12 to 20 reveal that the optimum thickness of the
intermediate layer is 0.05 .mu.m to 5 .mu.m.
The results of Sample No. 21 to 27 reveal that preferable total thickness
of the ultrafine particle-layered film is 0.5 .mu.m to 15 .mu.m.
The results of Sample No. 28 to 34 reveal that the optimum thickness of the
surface layer is 0.1 .mu.m to 5 .mu.m.
High wear-resistance and breakage-resistance were observed in Sample No. 47
having a composition modulated layer in which proportions of Ti and Al
changed continuously interposed between adjacent two layers of TiN and
AlN. Same results were observed also in Sample No. 48 having a composition
modulated layer in which proportions of TiZr and Cr changed continuously
and in Sample No. 49 having a layer of intermediate composition of
Hf.sub.0.6 Cr.sub.0.4 N between adjacent two layers of HfN and CrN.
EXAMPLE 2
Powder of TiN and powder of aluminium were mixed at a ratio of 80:20 by
weight in a pot made of cemented carbide alloy containing balls of the
same material to obtain a binder powder. Powder of CBN was mixed with the
binder powder at a ratio of 70:30 by volume and the resulting powder
mixture was sintered at 1,400.degree. C. under a pressure of 48 kb for 20
minutes in a container of Mo. The resulting sintered article was shaped
into a tip for cutting tool.
The ultrafine particle-layered film according to the present invention was
deposited on the resulting tip as substrate by the same method as Example
1 (Sample No. 101 to 131).
For comparison, the conventional coating films were deposited on tips
prepared by the same method (Sample No. 132 to 135). The results are
summarized in Table 3 and Table 4.
In Table 3 and Table 4, star mark (*) indicates examples outside the
present invention. For example, Sample No. 101 is outside the present
invention because its ultrafine particle-laminated film (total thickness
of 5.1 .mu.m) has a layer of TiN (0.8 nm) and of AlN (0.9 nm) and of
lamination cycle=1.7 nm.
Sample Nos. 132 to 135 are comparative examples of known cutting tips
having the conventional coating layers.
Sample Nos. 132 and 134 each have a hard coat layer of TiCN layer and/or
TiN layer prepared on a tip prepared by the same method as above by
ion-plating technique under vacuum arc discharge in usual film forming
machine.
Sample No. 133 has a hard coat layer of a combination of TiN and Al.sub.2
O.sub.3 layer prepared on a tip prepared by the same method as above by
usual CVD technique.
Wear-resistance of the resulting tips was determined by curing test in
which a round steel rod (SUJ2) having a hardness of HRC60 was cut along
its periphery at a cutting speed of 150 mm/min, a depth of cut of 0.2 mm,
a feed of 0.1 mm per revolution and for 20 minutes in a dry condition to
measure a flank wear width (mm). Results are summarized in Table 4.
TABLE 3
__________________________________________________________________________
sample
Intermediate layer
Surface layer
Wear-resitant layer
No material
thickness (.mu.m)
material
thickness (.mu.m)
material thickness (.mu.m)
__________________________________________________________________________
101 none
-- none
-- ultrafine particle-layered film
5.1
102 none
-- none
-- ultrafine particle-layered film
0.3*
103 none
-- none
-- ultrafine particle-layered film
0.6
104 none
-- none
-- ultrafine particle-iayered film
5.2
105 none
-- none
-- ultrafine particle-layered film
14.5
106 none
-- none
-- ultrafine particle-layered film
15.8*
107 none
-- none
-- ultrafine particle-layered film
5.1
108 none
-- none
-- ultrafine Particle-layered film
5.0
109 none
-- none
-- ultrafine particle-layered film
5.3
110 TiN 0.01* none
-- ultrafine particle-layered film
5.2
111 TiN 0.05 none
-- ultrafine particle-layered film
5.3
112 TiN 0.5 none
-- ultrafine particle-layered film
5.1
113 TiN 1.6 none
-- ultrafine particle-layered film
5.4
114 TiN 5.0 none
-- ultrafine particle-layered film
5.2
115 TiN 5.5* none
-- ultrafine paiticle-layered film
5.0
116 TiN 1.6 TiN 0.05* ultrafine particle-layered film
5.1
117 TiN 1.6 TiN 0.5 ultrafine particle-layered film
5.2
118 TiN 1.6 TiN 2.2 ultrafine particle-layered film
5.2
119 TiN 1.6 TiN 14.9 ultrafine particle-layered film
5.2
120 TiN 1.6 TiN 16.1* ultrafine particle-layered film
5.1
121 TiN 1.6 none ultrafine particle-layered film
5.3
122 TiN 1.6 none ultrafine particle-layered film
5.2
123 TiN 1.6 none ultrafine particle-layered film
5.1
124 TiN 1.6 none ultrafine particle-layered film
5.0
125 TiN 1.6 none ultrafine particle-layered film
5.2
126 TiN 1.6 none ultrafine particle-layered film
5.3
127 TiN 1.6 none ultrafine particle-layered film
5.1
128 TiN 1.6 none ultrafine particle-layered film
5.1
129 TiN 1.6 none ultrafine particle-layered film
5.2
130 TiN 1.6 none ultrafine particle-layered film
5.3
131 TiN 1.6 none ultrafine particle-layered film
5.3
132 TiN 1.6 TiN 2.0 TiCN coating layer
4.8
133 TiN 1.6 TiN 2.2 Al.sub.2 O.sub.3 coating layer by
1.0
134 none TiN 2.1 none
135 none none none
__________________________________________________________________________
Sample No. 132 to 135 are comparative.
TABLE 4
__________________________________________________________________________
Structure of ultrafine particle-layered film
materials thickness
lamination
maximum
Wear-resistance
of each layer
(nm) cycle
partical size
Flank wear
No.
(a)
(b) (a)
(b) (nm) (nm) (mm) Evaluation
__________________________________________________________________________
101
TiN
AlN 0.8*
0.9*
1.7 0.8* 0.145 bad
102
TiN
AlN 1.2
1.3 2.5 1.3 0.182 bad
103
TiN
AlN 1.2
1.3 2.5 1.3 0.129 good
104
TiN
AlN 2.5
2.4 4.9 2.5 0.120 good
105
TiN
AlN 2.5
2.4 4.9 2.5 0.119 very good
106
TiN
AlN 2.5
2.4 4.9 2.5 0.131 not good
107
TiN
AlN 18.4
18.5
36.9 18.5 0.125 good
108
TiN
AlN 47.8
46.2
94.0 47.8 0.129 good
109
TiN
AlN 52.3
51.0
103.3
52.3 0.139 not good
110
TiN
AlN 2.5
2.4 4.9 2.5 0.121 good
111
TiN
AlN 2.5
2.4 4.9 2.5 0.115 very good
112
TiN
AlN 2.5
2.4 4.9 2.5 0.115 very good
113
TiN
AlN 2.5
2.4 4.9 2.5 0.114 very good
114
TiN
AlN 2.5
2.4 4.9 2.5 0.116 very good
115
TiN
AlN 2.5
2.4 4.9 2.5 0.122 good
116
TiN
AlN 2.5
2.4 4.9 2.5 0.115 very good
117
TiN
AlN 2.5
2.4 4.9 2.5 0.109 very good
118
TiN
AlN 2.5
2.4 4.9 2.5 0.108 very good
119
TiN
AlN 2.5
2.4 4.9 2.5 0.119 very good
120
TiN
AlN 2.5
2.4 4.9 2.5 0.124 good
121
TiN
AlN 30.1
31.5
61.6 0.8* 0.139 not good
122
TiN
AlN 30.1
31.5
61.6 2.5 0.126 good
123
TiN
AlN 30.1
31.5
61.6 31.5 0.129 good
124
TiN
AlN 30.1
31.5
61.6 54 0.139 not good
125
ZrN
AlN 2.4
2.6 5.0 2.5 0.121 good
126
HfN
AlN 2.6
2.4 5.0 2.5 0.119 very good
127
VN AlN 2.4
2.5 4.9 2.5 0.118 very good
128
CrN
VN 2.5
2.6 5.1 2.5 0.124 good
129
TiN
VN 2.5
2.6 5.1 2.5 0.125 good
130
CrN
AlN 2.4
2.3 4.7 2.5 0.120 good
131
TiN (2.4)/AlN (2.3)/CrN (2.4)
7.1 2.5 0.124 good
132
-- -- -- -- -- -- 0.151 bad
133
-- -- -- -- -- -- 0.154 bad
134
-- -- -- -- -- -- 0.198 bad
135
-- -- -- -- -- -- 0.203 bad
__________________________________________________________________________
EXAMPLE 3
Procedure of Examples 1 was repeated but a film forming apparatus shown in
FIG. 6 was used (totally four targets of Ti and AlD were used) and a
laminated film was prepared from the same material under the same
conditions as Sample No. 118 (TiN layer=2.5 nm and AlN layer=2.4 nm).
The flank wear of this Example was 0.100 mm.
EXAMPLE 4
Procedure of Example 1 was repeated but the content (vol %) of CBN in the
substrate and compositions (wt %) of binder were changed to those shown in
Table 5. X-ray diffraction patterns of the resulting sintered articles
revealed existence of inevitable contaminations which were thought to be
.alpha.-Al.sub.2 O.sub.3, WC and Co.
The resulting CBN sintered body was shaped into a tip for cutting tool and
an intermediate layer of TiN having a thickness of 2 .mu.m was deposited
on portions of the tip where cutting participate by usual PVD technique
and then the ultrafine particle-layered film consisting of TiN and AlN
deposited alternatively to the total thickness of 5.3 .mu.m. TiN layer had
a thickness of 2.5 nm and AlN layer had a thickness of 2.4 nm. In
operation, the film forming apparatus shown in FIG. 5 was used.
Table 5 shows time until damage (=a time duration until the tool was
damaged: min) which was determined when a round steel rod of carburized
hardened SCM415 was cut by the resulting tools along its periphery.
TABLE 5
______________________________________
Time until
rupture (min)
Sample
CBN Composition of binder
no with
No (vol %) (% by weight) film.sup.1)
film.sup.2)
______________________________________
201 35 80:(TiHF)C, 20:TiB.sub.2, AIN, ASlB.sub.2
15 21
202 70 78:(TiW)N, 22:AlN, AlB.sub.2, TiB.sub.2
30 38
203 95 80:TiCN, 10:WC, 10:TiB.sub.2, AlN
10 17
204 45 70:CoWC, Co.sub.3 W.sub.3 B, 30:AlN, AlB.sub.2
20 30
205 80 80:CoWB, Co.sub.3 W.sub.3 B, 20:AlN
26 32
206 98 100:AlN 15 22
207 65 40:TiN, 20:VN, 20:HfC, 20:Aln, TiB.sub.2
41 21
208 99 100:Mg.sub.2 B.sub.2 N.sub.4, Li.sub.2 B.sub.2 N.sub.4
15 18
209 60 100:Al.sub.2 O.sub.3 1 3
210 20 60:TiN, 40:AlB.sub.2, TiB.sub.2
7 10
211 50 80:Cu, 20:TiN 3 6
______________________________________
Note
.sup.1) tools before ultrafine particlelayered film is deposited.
.sup.2) tools having ultrafine particlelayered film
EXAMPLE 5
A diamond sintered body was prepared from diamond powder, powder of iron
family element, and powder of at least one of carbide or carbonitride of
IVa, Va and VIa elements, WC, Si and SiC. The content of diamond and
combination of powders are summarized in Table 6. Material powder mixture
was sintered at 1,500.degree. C. under a pressure of 60 kb for 30 minutes
in a container of Mo. The resulting sintered article was shaped into a tip
for cutting tool.
On portions of the tip where cutting participate, an intermediate layer of
TiC (3 .mu.m) was deposited by the same method is Example 2 and then TiN
layer and AlN layer were deposited alternately by the same method as
Example 2 to obtain ultrafine particle-layered film (thickness of 5.2
.mu.m). Thickness of each layer was 2.5 nm and the lamination cycle was
5.0 nm. Operation was carried out in the apparatus shown in FIG. 5.
The resulting tips were evaluated by cutting test in which a round steel
rod prepared by a combination of FCD 600 and 16% Si--Al alloy (cutting
ratio=1:1) was cut along its periphery at a cutting speed of 200 mm/min, a
depth of cut of 0.3 mm, a feed of 0.2 mm per revolution for 20 minutes in
wet condition to measure a flank wear width (mm). Results are summarized
in Table 6.
TABLE 6
______________________________________
content of
Sample
diamond other components
Frank wear width (mm)
No (vol %) (% by weight)
no film.sup.1)
with film.sup.2)
______________________________________
301 45 TiC, Co, WC 0.187 0.143
302 70 TiN, Co, Ni, WC
0.171 0.120
303 95 TiCN, Co, WC
0.162 0.113
304 75 SiC, Si, WC 0.243 0.175
305 80 Co, Ni, TiC 0.159 0.212
306 98 Co, WC 0.208 0.156
307 85 TiC, HfC, Co
0.158 0.128
308 88 TiC, Co, WC 0.147 0.107
309 70 Al, Al.sub.2 O.sub.3
3 min (broken)
5 min (broken)
310 35 TiN, Co 2 min (broken)
6 min (broken)
311 99 Co, W 3 min (broken)
5 min (film
peeled off)
______________________________________
Note
.sup.1) tools before ultrafine particlelayered film is deposited.
.sup.2) tools having ultrafine particlelayered film
EXAMPLE 6
A silicon nitride sintered body was prepared from a powder mixture of
silicon nitride powder, aluminium oxide powder and yttrium oxide powder
mixed at proportions by volume of 95:3:2. The powder mixture was sintered
by HIP technique at 1,800.degree. C. under a pressure of 300 kg/cm.sup.3
for 30 minutes in N.sub.2 gas atmosphere. The resulting sintered article
was shaped into a tip for cutting tool.
On portions of the tip where cutting participate, an intermediate layer of
TiN (2 .mu.m) was deposited by CVD technique and then TiN layer (2.5 nm)
and AlN layer (2.4 nm) were deposited alternately by the same method as
Example 2 to obtain ultrafine particle-layered film (thickness of 7.9
.mu.m). Operation was carried out in the apparatus shown in FIG. 5.
The resulting tips were evaluated by cutting test in which a round steel
rod (FC25) was cut along its periphery at a cutting speed of 300 mm/min, a
depth of cut of 3 mm, a feed of 0.4 mm per revolution for 15 minutes in
dry condition to obtain following flank wear width (mm).
______________________________________
Tip tested (silicon nitride sintered body)
Flank wear width (mm)
______________________________________
having no ultrafine particle-layered film
0.185
having ultrafine particle-layered film
0.112
______________________________________
EXAMPLE 7
A aluminium oxide-titanium carbide sintered body was prepared from a powder
mixture of aluminium oxide powder, titanium carbide powder and yttrium
oxide powder mixed at proportions by volume of 70:29.5:0.5. The powder
mixture was sintered at 1,800.degree. C. for 30 minutes. The resulting
sintered article was shaped into a tip for cutting tool.
On portions of the tip where cutting participate, an intermediate layer of
TiN (3 .mu.m) was deposited by PVD technique and then TiN layer (2.5 nm)
and AlN layer (2.4 nm) were deposited alternately (lamination cycle is 2.4
nm) by the same method as Example 2 to obtain ultrafine particle-layered
film (thickness of 6.1 .mu.m). Operation was carried out in the apparatus
shown in FIG. 5.
The resulting tips were evaluated by cutting test in which a round Inconel
rod (aging treated material: HRC45) was cut along its periphery at a
cutting speed of 400 mm/min, a depth of cut of 1.0 mm, a feed of 0.15 mm
per revolution for 10 minutes in wet condition to obtain following flank
wear width (mm).
______________________________________
Tip tested (aluminum oxide-titanium carbide
Flank wear width
sintered body) (mm)
______________________________________
having no ultrafine particle-layered film
0.215
having ultrafine particle-layered film
0.098
______________________________________
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